Researchers: Farm fertilizer top nitrogen pollution cause for North Fork

The Nature Conservancy environmental group on Thursday released a report that details the sources of nitrogen pollution researchers say are reaching surface waters throughout the Peconic Estuary.

The data presented in the report shows causes of nitrogen pollution vary significantly throughout the East End.

As suspected by researchers and environmental experts, septic systems were found to be the largest single contributor of nitrogen overall in many areas of the estuary, measuring in at at 49.6 percent. Fertilizer from agriculture, lawns and golf courses came in second, accounting for 26.4 percent of inputs, while atmospheric deposits came in at 24 percent, according to overall numbers.

Full report available below.

But septic systems weren’t the leading source of nitrogen input in all areas of the region.

The study found agricultural fertilizer to be the top source of nitrogen pollution in areas of the Great Peconic Bay and Little Peconic Bay (more than 50 percent) on the North Fork’s southern shore, as well as around Long Beach Bay in Orient (77 percent).

“While we know that nitrogen pollution from sewage plagues nearly every water body on Long Island, this report provides a precise road map for policy makers seeking to reduce nitrogen by means of septic system and cesspool reforms,” said Nancy Kelley, the executive director of The Nature Conservancy on Long Island said.

High nitrogen levels in area waters have been feeding harmful algal blooms, which in turn have damaged the local ecosystem by depriving bodies of water of oxygen and negatively affecting area fisheries. Nitrogen levels have likewise been increasing in area drinking water.

Researchers used what is known as the Nitrogen Loading Model — a widely used model, in part because of its “ability to quantify sources of nitrogen with relative ease and accuracy, utilizing existing information about atmospheric deposition rates, on-site wastewater systems, sewage treatment plant outputs, fertilizer application rates, and spatial data on population, land use, and land,” according to the study.

Atmospheric deposit rates were calculated from a Cedar Beach monitoring location in Southold belonging to the National Atmospheric Deposition Program.

It was the only available site within the study area, researchers said.

“In deploying their nitrogen loading model, the Conservancy has specifically identified the sources of contamination from 43 areas in the Peconic,” Suffolk County Executive Steve Bellone said in response to the study’s release.

“It is this very specific scientific data that will provide a roadmap for Suffolk County as we set about reclaiming our waters.”

Mr. Bellone has been an advocate for getting a comprehensive law passed in Albany to tackle Long Island’s nitrogen problems.